In Long Term Evolution (Long Term Evolution, LTE) standards, it is generally considered that a time length of one transmission time interval (Transmission Time Interval, TTI) is 1 ms, that is, a size of one subframe (subframe, SF) is 1 TTI=1 ms=1 SF. One SF includes two timeslots (Slot). As shown in FIG. 1, in a subframe used for downlink transmission in an LTE communications system, one TTI may be divided into a control area used to transmit a physical downlink control channel and a data area used to transmit a physical downlink data channel. The physical downlink control channel is used to carry control information of the physical downlink data channel.
To shorten a transmission round-trip time (Round-Trip Time, RTT) of data and a transmission delay of data, the industry proposes a solution in which it is set that TTI=0.5 ms and 1 TTI=1 ms are compatible to perform data transmission. That is, as shown in FIG. 2, one original normal TTI (N-TTI for short) is divided into two shortened TTIs (S-TTI for short) that respectively correspond to two timeslots (a timeslot 0 and a timeslot 1) in one SF. An RTT of data is a time that starts when a transmitter sends data, where during this time the transmitter then receives an acknowledgment indication of a receiver, and stops at a next moment when the transmitter sends data to the receiver again.
As shown in FIG. 2, an N-TTI may be divided into a control area (a shadowed part) and a data area (a non-shadowed part). In the foregoing solution in which TTI=0.5 ms and 1 TTI=1 ms are compatible to perform data transmission, an S-TTI (an S-TTI 0) corresponding to the timeslot 0 is overlapped with the control area of the N-TTI, and therefore, the control area of the N-TTI may be reused for the S-TTI 0, and is used as a control area of the S-TTI 0 to transmit a PDCCH in the S-TTI 0. However, an existing problem is that an S-TTI (an S-TTI 1) corresponding to the timeslot 1 is located in the data area of the N-TTI, and the part is originally used to transmit a physical downlink data channel in the N-TTI, but the control area of the N-TTI cannot be reused for an S-TTI-1. In this case, user equipment does not know from which control areas the user equipment is to receive a physical control channel of the S-TTI-1. Because a control area of the S-TTI-1 cannot be determined, a physical control channel of TTI-1 cannot be transmitted by using the control area of the S-TTI-1, and consequently, a physical data channel of the S-TTI-1 cannot be transmitted.